Virtual Poster Session

Welcome to the Virtual Poster Session, a new and powerful tool for networking and information exchange. Here you can share your work, search though the poster library, and start a dialogue with others in your field. Each uploaded poster that pertains to force measurement and testing can currently be used to apply for an academic travel scholarship; please see the Scholarships page for application details and deadlines.

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Submitted by Gina DiGiacomo

When evaluation cognition, there is a certain complexity surrounding electroencephalographic (EEG) recordings, which would greatly benefit from being supplemented by secondary recordings, such as those from a force platform. Currently, there is also a lack of evidence supporting the need to implement creative exercise on analytical coursework, specifically in STEM degrees where there is gaining momentum to incorporate the arts [3]. This pilot study aims to correlate electroencephalography (EEG, Brain Vision) and postural sway (AMTI AccuSway) data to verify cognitive changes. This study hypothesizes that participants will have 1) increased EEG alpha activity and 2) increased postural sway when participating in iterations of a problem-solving tasks administered after the participant engages in creative activities. The study will use human-subject data gathered from electroencephalography (Brain Vision) and postural sway (AMTI AccuSway) to quantify the cognitive engagement of participants during the learning of new concepts in a unique manner that allows the participants to think about them visually. The hypothesis is that the teaching methods introduced will encourage participants to have increased cognitive attention. Two participants were evaluated on their postural sway and EEG activity during the answering of Raven’s Progressive Matrices tests before and after artistic viewing and drawing activities. The data generated by this study by these means will show that increased cognition is apparent when concepts are presented in a visual manner, fortifying a philosophy that engineering curricula would benefit from artistic additions.

Submitted by Jasper Verheul

Body-worn sensors are commonly used for field-based movement and load measurements to asses injury risks in sports. To further explore the feasibility of using accelerometers for assessing whole-body biomechanical loading, this study used principal component analysis (PCA) to identify important movements and their contribution to the ground reaction force (GRF) for tasks that are frequently performed during running-based sports. Fifteen team-sport athletes performed accelerated, decelerated and constant low- (2-3 m/s), moderate- (4-5 m/s) and high-speed (>6 m/s) running, and 90° cutting trials, while full-body kinematics and GRF data were collected with a three-dimensional motion capture system and force platform respectively. A PCA was performed on the combined marker trajectory matrices for each task to identify task-specific principal movements (PMs). Resultant principal ground reaction forces (PGRFs) were calculated from each PM and assessed by the root mean square error (RMSE) of the summed PGRFs (∑PGRF). Across tasks, PM1 primarily described anteroposterior body movements, but PGRF1 errors were very high (>4 N/kg). Vertical body compression was the dominant contributor to the overall GRF and was described by PM3 (cutting), PM2 (low-speed) or PM5 (moderate- and high-speed), but less important for accelerated (PM10) and decelerated running (PM7). These results demonstrate that fundamental movement features contributing to GRF profiles are task-specific, making generalised evaluations of GRF features across different activities using predefined movements (e.g. segment accelerations) is difficult. Future research should investigate if PMs and PGRFs can also be related to structure-specific measures of biomechanical load (e.g. joint moments).

Submitted by Erika Pliner

MOTIVATION: Ladder fall injury rates are highest among older adults. While standing stability has been quantified using center of pressure (COP) to classify general fall risk of older adults, it has not been applied to older adults’ balance and performance on ladders. This study investigates the standing stability of older adults while performing a task on a ladder.

METHODS: One-hundred four older adults completed the Physiological Profile Assessment (PPA) to classify fall risk and climbed to the second step of a household step ladder to change a light bulb. Force plates under the step ladder were used to calculate the COP. COP parameters were extracted to assess stability on the step ladder including path length (time-normalized), RMS and elliptical area.

Task time and COP parameters were compared between 10 participants with the highest fall risk and 10 participants with the lowest fall risk based on the PPA.

RESULTS: Task time was 8.4 seconds (63.9%) longer for the high fall risk group. Time-normalized path lengths were similar between the two groups. The high fall risk group showed an increase in RMS by 18.1% and elliptical area by 44.6%.

CONCLUSIONS: Differences in tasks time, RMS and elliptical area were observed between low and high fall risk groups. Larger RMS values and elliptical area indicate more movement away from the average COP location. This suggests high fall risk older adults to be more variable than low fall risk older adults in their standing stability when completing a task on a step ladder.

Submitted by Bruno Bedo

Fatigue is a case of interaction between different factors and is characterized by the increase in the perceived effort to exercise and produce force. However, the effect on balancing tasks are not completely understood, especially the time course of the postural sway parameters during the recovery phase. Twenty female handball athletes participated in this study. They stood upright in a one-leg posture supported by the non-dominant limb on a force plate. The center of pressure (COP) and the maximum propulsion force (FMAX) were obtained at baseline, immediately after the exhaustion due to the fatigue protocol and every minute during the first 10 min of the recovery phase. For the postural-sway measures, participants stood on the force plate for 30 s with eyes opened looking to a target. Based on the COP displacement, the ellipse area containing 95% of the COP data points (Area) was computed. The FMAX was measured during a countermovement jump. Specific handball actions composed the fatigue protocol in the format of a circuit with the gradual increment of laps. The force decreased ~9.5% after the fatigue protocol (p = 0.01) and returned to baseline values during the recovery phase at the fifth minute. For the postural sway, the Area decreased during the recovery phase until the fourth minute (p = 0.007). The fatigue protocol affected postural sway and force variables, which returned to baseline values after four minutes of the protocol. Therefore, we suggest that future fatigue analyses should be tested during this time window.

Submitted by Noelle Tuttle

Generalized joint laxity (GJL) is a condition in which most joints of the body move beyond the accepted normal range of motion. It allows for greater flexibility, which is beneficial to sports such as dance, but can lead to musculoskeletal injuries and decreases in strength. The ability to control landings with strength and stability is key to high level dance performance. Therefore, the purpose of this study was to evaluate differences in peak ground reaction force (GRF; vertical, medial-lateral, and anterior-posterior), during landing between dancers with and without GJL. Twenty healthy female volunteers with experience in ballet or modern dance were screened for GJL using the Beighton Scale. 10 subjects with GJL (score of 6 or higher) and 10 without GJL (score of 3 or below) were selected for testing. Subjects performed three forward, unshod, single-leg drop landings from a height of 40 cm onto a portable force plate (Bertec Corporation, OH, USA). Peak GRF for each landing was found and averaged for each subject, and for each group. No significant differences were found in peak GRF in any direction (p=0.71). We believe the similarity in peak forces between groups is due to dancers’ training and technique, as dancers are expected to control and soften their landings. GRF provides information about the load placed on the body, but lacks details related to landing technique. Further research describing 3D landing kinematics, joint moments, and muscle activation is required to determine if different landing techniques exist between dancers with and without GJL.

Listed In: Biomechanics
Submitted by Stephanie Cone

The anterior cruciate ligament (ACL) stabilizes the lower limb against translational and rotational loads while the knee is is multiple postures. Surgical reconstruction, the most common treatment for ACL tears, is intended to replicate the biomechanical function of the native ACL in the postures and activities related to daily living and high-impact activities. In order to improve outcomes from ACL reconstructions in patients in pediatric and adolescent age groups, we need to improve our understanding of the knee posture dependent biomechanical function of the ACL. As such, the objective of this study was to quantify flexion angle dependent changes in the response of the ACL and the total knee to applied loads in the anterior-posterior and varus-valgus directions using a skeletally immature porcine model. To do this, we collected stifle (knee) joints from female Yorkshire-cross pigs at ages ranging from 1.5 to 18 months (n=30 total). The joints were tested using a 6 degree-of-freedom universal force sensing robotic system under applied anterior-posterior loads and varus-valgus moments at 40° and 60° of flexion. Studied parameters included anterior-posterior tibial translation (APTT), varus-valgus rotation (VVR), and anterior force carried by the ACL and its anteromedial and posterolateral bundles. We found increased knee laxity (APTT and VVR) was associated with both younger age and increased knee flexion. Greater anterior force carried in the ACL, and specifically in the anteromedial bundle, was associated with increased flexion, regardless of age. These findings have implications in intraoperative graft assessment and biomechanical models.

Submitted by Steven Garcia

Obesity and female sex are considered independent risk factors for the development of knee osteoarthritis (KOA) which may be due to aberrant gait biomechanics. Few data exist on the interaction of obesity and female sex despite their independent influence on KOA risk. The purpose of this study was to examine the influence of sex and BMI on knee joint sagittal and frontal plane gait mechanics. Dependent variables included the knee flexion moment (KFM) and first peak knee adduction moment (KAM1). Gait biomechanics were assessed in 42 obese and 39 normal weight participants that were matched on age and sex. Kinematic and kinetic data were sampled using a 9-camera Qualisys system and 2 AMTI force-plates. Participants completed walking trials in laboratory standard neutral-cushion footwear at self-selected speed and the external KFM and KAM1 during the first 50% of stance was extracted and normalized to a product of bodyweight (N) and height (m). A 2 (BMI) by 2 (Sex) analysis of co-variance (α=0.05) was used to examine dependent variables with gait speed as a covariate. The BMI by sex interaction was not significant for KFM (p=0.073) or KAM1 (p=0.703). A main effect was observed for sex and females exhibited smaller KFM (p=0.05) and greater KAM1 (p=0.004) compared to males. No differences were found in normalized knee moments between BMI groups. Regardless of BMI, females exhibited aberrant gait mechanics that are indicative of KOA progression. Further studies are needed examining the influence of altered gait in young, healthy females on knee cartilage morphology.

Listed In: Biomechanics, Gait
Submitted by Lauren Schroeder

Noncontact ACL injuries occur during movements that involve sudden decelerations and changes in direction due to combined sagittal and frontal plane knee loading. Previous studies have shown altered knee mechanics when decision-making is involved, which may better simulate game-like scenarios in a lab setting. The purpose of this study was to determine how two unanticipated stimuli alter knee biomechanics during a dynamic task. Eight females and eight males, all recreationally-active, participated. Participants completed two unanticipated 45-degree cutting conditions (visual stimulus (VS); human defensive opponent (DO)). For the VS condition, a custom computer program presented one of three visual stimuli in a random order. For the DO condition, a research assistant attempted to “block” the participant’s running path with a defensive move, using the same three random-order tasks as in VS. For both conditions, participants had a reaction time range of 400-500 milliseconds. Separate 2×2 mixed-model repeated measures ANOVAs (condition×sex) were performed, with an alpha level of .05. Results showed a significant condition main effect for knee extension moments, which were greater in DO compared to VS (p=.009). Significant interactions were present for peak knee flexion angles and peak knee adduction moments. Females had greater flexion angles (p=.001) and adduction moments (p=.030) in VS compared to DO. Women had less knee flexion and more adduction moment in VS, possibly suggesting this stimulus amplifies ACL injury risk factors in females. A human defender increased sagittal plane loading in a manner that may better represent loading in game situations.

Submitted by Tanner Thorsen

Q-Factor (QF), the inter-pedal width, in cycling is the analog to step-width in gait. Increased step-width has been shown to reduce peak knee abduction moment (KabM), however no studies have examined the frontal plane biomechanics with increased QF in cycling. The purpose of this study was to investigate the effects of increased QF on frontal plane knee biomechanics during cycling in healthy participants. Sixteen healthy participants (age: 22.4 ± 2.6 yr, BMI: 22.78 ± 1.43 kg/m2) participated in this study. A motion analysis system and customized instrumented pedals were used to collect five trials of three-dimensional kinematic (240 Hz) and pedal reaction force (PRF, 1200 Hz) data in twelve testing conditions, four QF conditions of Q150 (150 mm), Q192 (192 mm), Q234 (342 mm), Q276 (276 mm), and three workrate conditions of 80 W, 120 W, and 160 W. A 3 × 4 (QF × workrate) repeated measures ANOVA was performed to analyze differences between conditions (p < 0.05). Increased QF increased peak KAbM 47, 56, and 56% from Q150 to Q276 at each workrate respectively. Mediolateral PRF increased 46, 57, and 57% from Q150 to Q276 at each workrate. Frontal plane knee angle and range of motion (ROM) decreased with increased QF. No changes were observed for peak vertical PRF, knee extension moment, sagittal plane peak knee joint angles or ROM. Conclusions: These results indicate increasing QF will increase peak KAbM. Future studies should examine the effects of increased QF on obese and knee osteoarthritis patients.

Submitted by Shelby Peel

Females commonly use a landing technique that creates higher impact forces when contacting the ground, thus leading to higher ground reaction force (GRF) acting upon the lower extremities, leading to an increased risk of injury. The lower extremity musculature plays a critical role in absorbing the energy of these impact forces during landing. Understanding how specific muscle groups contribute to ground reaction force may offer insight to creating more advanced landing retraining protocols. The purpose of this study was to observe how lower extremity muscle groups contribute to GRFs during an unanticipated stop-jump task. 3D musculoskeletal simulations of unanticipated stop-jump tasks were completed for five healthy females. Participant-specific scaled musculoskeletal models (modified gait2392) were generated. A pseudo-inverse induced-acceleration analysis was used to determine individual muscle group contribution to 3D GRFs. Means ± standard deviations were calculated for each muscle group during the landing phase. The vasti, soleus, and the gluteus maximus muscle groups were most responsible for bodyweight support, with the vasti and the soleus being the largest contributors (375.84±88.64 N; 267.39±103.70 N, respectively). The vasti group (165.63±74.94 N) were primarily responsible for braking and propulsion. Finally, the gluteus maximus, gluteus medius, and vasti group were the major generators in producing a medially-directed GRF, with the vasti group as the largest contributor (118.05±32.83 N). The vasti, soleus, and gluteus maximus appears to be the overall largest contributors to 3D GRFs. Landing retraining protocols may want to consider targeting these muscle groups specifically to improve landing performance and decrease injury risk.